Update prebuilts to go1.7rc1 ab/3043704

toolchain/go sha ffb9ee3a

Change-Id: Id13cc2f426fd6d4e53bde9b50251fb264a647f47
diff --git a/src/cmd/go/go_unix_test.go b/src/cmd/go/go_unix_test.go
new file mode 100644
index 0000000..c445a2e
--- /dev/null
+++ b/src/cmd/go/go_unix_test.go
@@ -0,0 +1,31 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build darwin dragonfly freebsd linux netbsd openbsd solaris
+
+package main_test
+
+import (
+	"os"
+	"syscall"
+	"testing"
+)
+
+func TestGoBuildUmask(t *testing.T) {
+	// Do not use tg.parallel; avoid other tests seeing umask manipulation.
+	mask := syscall.Umask(0077) // prohibit low bits
+	defer syscall.Umask(mask)
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.tempFile("x.go", `package main; func main() {}`)
+	tg.creatingTemp("x")
+	tg.run("build", tg.path("x.go"))
+	fi, err := os.Stat("x")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if mode := fi.Mode(); mode&0077 != 0 {
+		t.Fatalf("wrote x with mode=%v, wanted no 0077 bits", mode)
+	}
+}